What compiler, and OS are you using perhaps if you are using a windows compiler it doesn't recognise the forward slash because windows uses a backslash (\) to signify different directories. That's is all that I can think of because if the file name is exactly spelt correctly(case sensitive), it should work?

What compiler, and OS are you using perhaps if you are using a windows compiler it doesn't recognise the forward slash because windows uses a backslash (\) to signify different directories. That's is all that I can think of because if the file name is exactly spelt correctly(case sensitive), it should work?

The win32 API functions accept forward and back slashes interchangeably in paths.

The file might be there, but the filename has probably being munged, or something is preventing the file being opened (eg file protections, another process having the file open for writing).

If the drive on which the files are stored has a FAT file system (which supports only the 8.3 filename scheme) the filename may be munged, so the file appears on disk with a different name. This may also be relevant if the compiler is relatively old, and converts the long file name (this filename exceeds the 8.3 spec) into an 8.3 name, and attempts to actually open that.

It is possible the filename is actually something that is visually similar but actually different. For example idngram2lm.h versus idngram2Im.h

Right 98% of the time, and don't care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

Tell us your OS and compiler.
Make sure something isn't using the file.
Although it shouldn't be an issue, but try re-naming a copy of the same file with just alphabetical letters (I notice that's the only thing that differs the problematic file from the others).

A hundred Elephants can knock down the walls of a fortress... One diseased rat can kill everyone inside